The visionmedia debug module correctly reports a deprecation warning whenever process.env.DEBUG_FD is used. The reason this is an IDEA issue is because WebStorm sets the deprecated DEBUG_FD environment variable before running a NodeJS configuration.

Expect a lot of traffic on this because the warning comes from the debug module, a dependency of the connect module, a dependency of the express module. Everyone running an express app will see this deprecation warning when running within WebStorm, and not when running outside of WebStorm.

Okay I see, the error is from the debug npm lib that is referenced from a few dependencies. If you're removed your setting of the environment variable, it would seem that does indeed clear JetBrains of any further work. It does imply that someone else is setting it though, unfortunately, but that means attention on the issue should be elsewhere. Okay good, at least I know JetBrains has already done their part.